Journal: Clinical calcium
Late-onset hypogonadism (LOH) is defined as the condition caused by the decline of testosterone by aging, along with various symptoms, including physical, psychological and sexual disturbance. Thus the principle of treatment for LOH is Androgen replacement therapy (ART) , and ART has been applied primarily in order to alleviate the various symptoms in LOH patients. The indication of ART for LOH is determined based on LOH symptoms assessed by aging males' symptoms (AMS) score and serum free testosterone levels. In abroad, several routes are available for the administration of testosterone, such as injection, patch, oral administration, etc. In Japan, intramuscular injection of testosterone enanthate every 2 to 4 weeks is widely indicated for treatment of LOH. It has also reported that ART using testosterone ointment once or twice a day appeared to improve those LOH symptoms. ART is a significant and safe procedure for anti-aging in male.
Accumulating evidence clearly indicates both thyroid hormone and estrogen have a pivotal role in bone metabolism. Pituitary hormones, TSH and FSH, regulate circulating levels of thyroid hormone and estrogen, respectively. Recent works raise a possibility that either TSH or FSH also has its own direct effects on bone cells involved in bone resorption and formation. More recently, it is suggested that oxytocin and vasopressin are also involved in bone metabolism. However, several investigations of genetically manipulated model mice and clinical data from patients with certain diseases have provided inconsistent results. Thus, we need more data that answer the question whether or not each pituitary hormone is physiologically and pathophysiologically involved in controlling bone metabolism in human.
Teriparatide, 1-34 parathyroid hormone, is one of effective treatments for osteoporosis. Teriparatide shows an anabolic effect for bone formation, as a result, increases bone mineral density as well as prevention of fractures in the general population. On the other hand, there are a few report about the effect of teriparatide on increase of bone mineral density in maintenance hemodialysis patients. In addition to CKD-MBD, osteoporosis is also an important pathological change in ESRD patients, therefore its safety and efficacy should be discussed in more detail.
Osteocytes are the most abundant osteolineage cells in the bone tissue, and they control the balance of activity between osteoblasts and osteoclasts in bone metabolism. Recent studies have revealed that the bone equipped with osteocytes controls not only bone marrow hematopoiesis but also regulates the functions of remote organs/tissues such as thymus and fat. Communications of bone cells with hematopoiesis, immunity and energy metabolism are overviewed.
Nearly nine years ago, new mechanism that bone secretes a hormone called osteocalcin and regulates glucose/energy metabolism was discovered. To date the study of osteocalcin as the bone hormone was progressed well, and the new roles in various tissues, such as glucose metabolism, male fertility, and development of the brain, are demonstrated. On the other hand, signaling pathway of osteocalcin has not yet been fully understood, though its receptor was reported. This review focuses on the diverse roles of osteocalcin and also on the future task that should be solved.
Nanoindentation has been applied in recent years to measure the mechanical properties of bone tissues at a microscopic scale, overcoming the limitations of traditional mechanical testing techniques for small samples. This method is precise and accurate and appears well suited for measuring mechanical properties in bone. Dynamic nanoindentation is also a promising method of measuring the viscoelastic properties of bone tissues at smaller length and load scales than allowed by other testing methods, thus allowing individual constituents and local regions of inhomogeneous tissues to be characterized individually. This article describes our nanoindentation studies of bone tissues with recent studies.
This is a brief report on ASBMR 2018 held at Montreal, Quebec, Canada, focusing on basic research. Topics of ASBMR 2018 were varied among wide research fields, however, this report focuses on several topics because of spatio-temporal restriction of attendees. Also, the selected topics were very limited according to the author’s interests.
Growth spurts of the bone occur during infancy(1 to 4 years)and puberty(12 to 17 years). While, generally, pubertal spurts appear to draw more attention than infantile spurts, the latter constitute maximum growth spurts. Indeed, those during the first year of life lead to a 1.5-fold increase in height or a height increase of 25 cm, thus representing the greatest of all growth spurts that occur in humans during their lifetimes. Again, while height growth continues through the first 3 years of life, nutrition represents the single greatest contributing factor to height growth during this period. Again, while, as with other organ primordia, the bone primordium is formed during the organogenesis stage, calcification becomes most active during the third trimester of pregnancy. Thus, this review provides an overview of bone growth in humans, in relation to bone/calcium metabolism, which begins in the fetal stage before birth and continues through infancy and puberty, finally leading to attainment of peak bone mass in humans.
Calcium metabolism changes dramatically during pregnancy and lactation because offspring needs a supply of calcium. Approximately 30g of calcium, which passes through the placenta, is accumulated in a fetus during pregnancy mostly in the third trimester, and 220-340mg/day of calcium is supplied via breast milk during lactation. However, there are elaborate mechanisms to maintain maternal calcium homeostasis, which differs during pregnancy and lactation. Extra required calcium supply to the offspring in neither pregnancy nor breastfeeding normally do not cause any adverse consequences to the maternal skeleton even if any oral intake of calcium or vitamin D are increased. This article reviews the adaptation in calcium kinetics during pregnancy and lactation. Vitamin D, calciotropic hormones, and bone metabolism are also reviewed.
In young women, why bone and calcium become a problem, it is because it is possible to delay the reach of the fracture threshold, even if the bone density in the future is acquired high bone density(bone mineral density:BMD)in the young period. In addition, the acquisition of maximum bone mass(peak bone mass:PBM)is an effective intervention to prevent future osteoporosis for around 18 years old before the age of 18. Factors that affect bone density include nutrition, dietary habits, physical activity, load movement, UV irradiation, estrogen deficiency, aging, and lifestyle-related diseases. In this section, it explains the condition and the disease which causes estrogen deficiency by low weight at an important time for the metabolism of the bone and calcium of young woman.